Graft polymers having oligoalkylenimine side chains, process for their preparation and their use

ABSTRACT

Graft polymers whose grafting base is selected from the group consisting of polymers having vinylamine units, polyamines, polyamidoamines and polymers of ethylenically unsaturated acids and which comprise exclusively oligoalkylenimine side chains as side chains, process for the preparation of graft polymers having oligoalkylenimine side chains, at least one oligoalkylenimine which comprises a terminal aziridine group being grafted onto one of said grafting bases, and the use of the graft polymers thus obtainable as process chemicals in the production of paper, as antimicrobial coating materials, as builders in detergents and for the treatment of metal surfaces.

The invention relates to graft polymers which comprise exclusivelyoligoalkylenimine side chains as side chains and whose grafting base isselected from the group consisting of polymers having vinylamine units,polyamines, polyamidoamines and polymers of ethylenically unsaturatedacids, process for the preparation of graft polymers havingoligoalkylenimine side chains, at least one oligoalkylenimine whichcomprises a terminal aziridine group being grafted onto one of thegrafting bases mentioned, and the use of graft polymers thus obtainableas process chemicals in the production of paper, as antimicrobialcoating materials, as builders in detergents and for the treatment ofmetal surfaces.

U.S. Pat. No. 3,280,218 discloses graft polymers of ethylenimine onpolyacrylic acid and/or polymethacrylic acid. These are comb polymerswhich comprise ethylenimine units as side chains. The molar massdistribution of the graft branches formed is broad. The graft branchesmay consist, for example, of only one ethylenimine unit or a pluralityof alkylenimine units. A serious disadvantage of the grafting ofpolymers with ethylenimine is a very long duration of reaction which isnecessary in order to suppress the formation of homopolymers ofethylenimine. The graft polymers are used as wet strength agents in theproduction of paper.

U.S. Pat. No. 3,492,289 discloses polyalkylenimines having molar massesof from 300 to 3000, which have an intact terminal aziridine ring. Theyare prepared by polymerization of alkylenimines in the presence oftrialkylaluminums, an acid or a Lewis acid as a catalyst in a virtuallyanhydrous solvent, such as benzene, toluene, n-heptane, cyclohexane or2-ethylhexane. The polymers can be used as bactericides or as curingagents for epoxy resins.

WO 01/36500 discloses monomers comprising alkylenimine units and of theformula

where

-   R is hydrogen or C₁- to C₄-alkyl, —[Al]_(m) is a linear or branched    oligoalkylenimine chain having m alkylenimine units,-   m is an integer in the range from 1 to 20, and the number average m    in the oligoalkylenimine chains is at least 1.5,-   Y is the anion equivalent of a mineral acid and-   n is a number where 1≦n≦m.

Monomers or monomer mixtures in which, in the abovementioned formula,the number average of m is at least 2.1, in general from 2.1 to 8, arepreferred. They are obtainable by reacting an ethylenically unsaturatedcarboxylic acid with an oligoalkylenimine, preferably in the form of anoligomer mixture. The product obtained thereby can, if appropriate, beconverted into the acid addition salt with a mineral acid HY. Suchmonomers can be polymerized in an aqueous medium in the presence of aninitiator which initiates a free radical polymerization to give homo-and copolymers which are used as assistants in papermaking.

Further dendritic macromonomers and polymers prepared therefrom aredisclosed in EP-A 1 524 314. The macromonomers are prepared, forexample, by reacting an adduct of ethylene oxide and polyethyleniminewith allyl glycidyl ether. Copolymers of these macromonomers withacrylic acid are used as builders in detergents.

The prior European patent application 07 117 909.7 discloses aminoalkylvinyl ethers comprising alkylenimine units and of the formula

H₂C═CH—O—X—NH—[Al]_(n)—H  (I)

where

-   [Al]_(n) is a linear or branched oligoalkylenimine chain having n    alkylenimine units,-   n is a number which is at least 1 and-   X is a straight-chain or branched C₂- to C₆-alkylene group, and    salts of the monomers I with mineral acids or organic acids and    quaternization products of the monomers I with alkyl halides or    dialkyl sulfates.

Polymers which comprise monomers with the formula I incorporated in theform of polymerized units are used, for example, as fixing agents in theproduction of paper, as antimicrobial coating materials, in detergentsand for the treatment of metal surfaces.

It is the object of the invention to provide further polymers havingalkylenimine units.

The object is achieved, according to the invention, by graft polymerswhich comprise alkylenimine units as side chains and whose base polymeris selected from the group consisting of polymers having vinylamineunits, polyamines, polyamidoamines and polymers of ethylenicallyunsaturated acids, if they comprise exclusively oligoalkylenimine sidechains as alkylenimine units.

The oligoalkylenimine side chains comprise, for example, from 2 to 50alkylenimine units, in general from 3 to 30 alkylenimine units,preferably from 3 to 15 alkylenimine units. Oligoalkylenimine sidechains which comprise from 5 to 10 alkylenimine units are particularlypreferred. Linear oligoalkylenimine side chains [Al]_(n) can bedescribed, for example, with the aid of the following formula

—[CHR′—CHR″—NH]_(n)—H  (II)

where n is a number of at least 2 and R′ and R″ are monovalent organicradicals, such as C₁- to C₄-alkyl, phenyl or hydrogen. R′ and R″ arepreferably hydrogen. In addition, branched oligoalkylenimine side chains[Al]_(n) are suitable. They can be characterized, for example, with theaid of the following formula

where p is 0 or an integer other than 0, i.e. 1, 2, 3, etc., q and r,independently of one another, are integers other than 0 and the sump+q+r+1=n, where n is at least 2 to 50, in general 3 to 30, preferably 3to 15 and in particular 5 to 10. The formula III represents a singlybranched oligoalkylenimine unit [Al]_(n) but multiple branchings arealso possible.

Graft polymers whose oligoalkylenimine side chains consist ofethylenimine units are particularly preferred.

The oligoalkylenimine side chains may be present in the form of the freebases or as salts. For example, mineral acids, such as hydrochloricacid, sulfuric acid, phosphoric acid, phosphonic acid or nitric acid,and saturated organic acids, such as formic acid, acetic acid, propionicacid, benzenesulfonic acid, amidosulfonic acid or p-toluenesulfonicacid, are suitable for salt formation. The nitrogen atoms of the sidechains can be completely or partly neutralized with an acid. Inaddition, it is possible for them to be present in quaternized form.They can be partly or completely quaternized, for example, with methylchloride, ethyl chloride, n-propyl chloride, isopropyl chloride, n-butylchloride, sec-butyl chloride, n-hexyl chloride, cyclohexyl chloride,benzyl chloride, methyl bromide, methyl iodide, ethyl bromide, ethyliodide, dimethyl sulfate or diethyl sulfate.

The graft polymers according to the invention comprise, for example,from 1 to 100 mol %, in general from 20 to 80 mol %, preferably from 30to 60 mol %, of at least one oligoalkylenimine per functional monomerunit in the base polymer. Functional monomer unit in the base polymer isto be understood as meaning, for example, vinylamine units in the caseof the polymers comprising vinylamine units or primary or secondaryamino groups in the case of the amines or polyamidoamines, and acidgroups, preferably carboxyl groups, in the case of the polymers havingacid groups.

The invention also relates to a process for the preparation of graftpolymers having oligoalkylenimine side chains, at least oneoligoalkylenimine which comprises a terminal aziridine group beinggrafted onto a grafting base selected from the group consisting ofpolymers having vinylamine units, polyamines, polyamidoamines andpolymers of ethylenically unsaturated acids.

Oligoethylenimines which comprise a terminal aziridine group arepreferably used as the oligoalkylenimine. Together with the aziridinegroup, the oligoalkylenimines consist of from 2 to 50 alkylenimineunits, in general from 3 to 30, preferably from 3 to 15 and inparticular from 5 to 10, alkylenimine units. The preparation of suchcompounds is known, cf. U.S. Pat. No. 3,492,289 mentioned above inrelation to the prior art.

For example, polymers having vinylamine units, polyamines,polyamidoamines and polymers of ethylenically unsaturated acids aresuitable as the grafting base onto which at least one oligoalkyleniminewhich has an intact aziridine group is grafted. The molar mass M_(w)(determined with the aid of gel permeation chromatography) of thesepolymers is, for example, from 500 to 1 million, preferably from 1000 to500 000, in particular from 2000 to 350 000.

Polymers comprising vinylamine units are obtainable by hydrolysis ofpolymers comprising vinylformamide units. Polyvinylamines are prepared,for example, by hydrolysis of homopolymers of N-vinylformamide, thedegree of hydrolysis being, for example, up to 100%, in general from 70to 95%. Copolymers of N-vinylformamide with other ethylenicallyunsaturated monomers, such as vinyl acetate, vinyl propionate, methylacrylate, methyl methacrylate, acrylamide, acrylonitrile and/ormethacrylonitrile, can be hydrolyzed to polymers comprising vinylamineunits and can be used according to the invention as the grafting base.The polymers comprising vinylamine units are cationic. In the hydrolysisof polymers of N-vinylformamide with acids, the salts of the polymers(ammonium salts) form, while polymers carrying amino groups form in thehydrolysis with bases, such as sodium hydroxide solution or potassiumhydroxide solution. The preparation of homo- and copolymers ofN-vinylformamide and the preparation of the polymers obtainabletherefrom by hydrolysis and having amino or ammonium groups are known.They are described in detail, for example, in U.S. Pat. No. 6,132,558,column 2, line 36 to column 5, line 25. The statements made there arehereby incorporated in the disclosure content of the present applicationby reference.

From this group of base polymers, polymers which have vinylamine unitsand comprise at least 50 mol % of vinylamine units are preferably used.

Polyamidoamines are also suitable as the grafting base. As is known,they are prepared by condensation of polycarboxylic acids, preferablydicarboxylic acids, with polyamines. For example, at least onedicarboxylic acid having 4 to 10 carbon atoms in the molecule issubjected to condensation with at least one polyalkylenepolyamine whichcomprises from 3 to 10 basic nitrogen atoms in the molecule. Suitabledicarboxylic acids are, for example, succinic acid, maleic acid, adipicacid, glutaric acid, suberic acid, sebacic acid or terephthalic acid.Examples of polyalkylenepolyamines are diethylenetriamine,triethylenetetramine, tetraethylenepentamine, dipropylenetriamine,tripropylenetetramine, dihexamethylenetriamine, dipropylenetriamine,tripropylenetetramine, dihexamethylenetriamine,aminopropylethylenediamine and bisaminopropylethylenediamine. In thepreparation of polyamidoamines it is of course also possible to usemixtures of polycarboxylic acids or mixtures of polyalkylenepolyamines.In order to prepare polyamidoamines, at least one dicarboxylic acid andat least one polyalkylenepolyamine are heated to relatively hightemperatures, for example to a temperature in the range from 120 to 220°C., in general in the range from 130 to 180° C. The water forming duringthe condensation is removed from the reaction mixture. Lactones orlactams or carboxylic acids having 4 to 8 carbon atoms can, ifappropriate, also be used in the condensation. For example, from 0.8 to1.4 mol of a polyalkylenepolyamine are used per mole of a dicarboxylicacid.

Modified polyamidoamines can also be used as the grafting base. Themodified polyamidoamines include, for example, crosslinkedpolyamidoamines which are obtainable by reaction of polyamidoamines withat least one crosslinking agent with the formation of water-solubleproducts. Suitable crosslinking agents are, for example, epichlorohydrinor bischlorohydrin ethers of alkylene glycols and/or polyalkyleneglycols. The polyalkylene glycols may comprise, for example, from 2 to100 alkylene oxide units.

Further examples of modified polyamidoamines are polyamidoamines whichhave been grafted with ethylenimine and reacted with at least onecrosslinking agent to give water-soluble products. In order to graftpolyamidoamines with ethylenimine, they are reacted, for example in thepresence of sulfuric acid or boron trifluoride etherates as a catalyst,in an aqueous medium with ethylenimine at temperatures of from 80 to100° C. Compounds of this type are described, for example, in DE-B 24 34816.

In addition, polyalkylenepolyamines, e.g. polyalkylenepolyamines havingmolar masses M_(w) of, for example, from 300 to 15 000, preferably from1000 to 12 000, and polyethylenimines are suitable as the grafting basefor the preparation of the products according to the invention.

Other suitable grafting bases are homo- and/or copolymers ofethylenically unsaturated acids. Examples of these are polymers ofethylenically unsaturated C₃- to C₅-carboxylic acids, such as acrylicacid, methacrylic acid, maleic acid, itaconic acid, fumaric acid,crotonic acid, vinyllactic acid or vinylacetic acid,acrylamidomethylpropanesulfonic acid or vinylphosphonic acid.Polyacrylic acid, polymethacrylic acid, copolymers of acrylic acid andmethacrylic acid and copolymers of acrylic acid and maleic acid arepreferred from this group of polymers.

In the graft polymerization, for example, from 1 to 100 mol %, ingeneral from 20 to 80 mol % and preferably from 30 to 60 mol % of atleast one oligoalkylenimine which comprises an intact aziridine ring areused per functional monomer unit in the grafting base.

The preparation of the products according to the invention is preferablyeffected in an aqueous medium in the presence of a catalyst, for examplea mineral acid, such as hydrochloric acid or sulfuric acid. The pH ofthe reaction mixture is, for example, in the range from 5.5 to 12,preferably from 6 to 11.

The reaction is carried out, for example, in such a way that first thecatalyst is added to an aqueous solution of the grafting base, themixture is heated to the reaction temperature and then theoligoalkylenimine which has an intact terminal aziridine group ismetered in continuously or batchwise. The reaction temperature is, forexample, in the range from 55 to 110° C., preferably from 85 to 100° C.The duration of the reaction is mainly dependent on the size of thebatch and the reaction temperature. It is, for example, in the rangefrom 30 minutes to 2 hours. The end point of the reaction, i.e. the timewhen aziridine groups are no longer detectable in the reaction mixture,can be determined with the aid of the reaction of aziridines with4-(4-nitrobenzyl)pyridine, cf. R. Preussmann, H. Schneider and F. Epple,Arzneimittel-Forschung, Volume 19, 1059-1073 (1969). In this test,aziridine groups are recognized on the basis of an intense violet color.If the test is negative, the reaction is complete. The reaction mixturecan be used directly. However, it is also possible to isolate the graftproducts according to the invention from the reaction mixture.

With the aid of the process according to the invention, it is possibleto prepare graft polymers having defined side chains. A furtheradvantage of this process is that the formation of homopolymers as abyproduct is greatly suppressed compared with the grafting ofethylenimine. The process according to the invention gives graftproducts in which the molecular weight distribution of the graftbranches is by far not as broad as in the case of the grafting withethylenimine.

The graft polymers according to the invention which comprise exclusivelyoligoalkylenimine side chains as alkylenimine units are used, forexample, as process chemicals in the production of paper. Graft polymershaving molar masses M_(w) (determined with the aid of gel permeationchromatography) of up to 30 000 are suitable in particular as fixingagents for pitch and crill in papermaking. The graft polymers accordingto the invention can also be used as antimicrobial coating materials, asbuilders in detergents and for the treatment of metal surfaces.

EXAMPLES

The polymers were characterized by means of gel permeationchromatography (GPC) and in some cases coupled with multi-angle laserlight scattering (GPC-MALLS).

The amine number was determined by potentiometric titration according toDIN 53176.

The end point of the reaction with aziridine-containing species wasdetermined with the aid of the reaction with 4-(4-nitrobenzyl)pyridine,cf. R. Preussmann, H. Schneider and F. Epple, Arzneimittel-Forschung,Volume 19, 1059-1073 (1969). Aziridines are recognized in said test with4-(4-nitrobenzyl)pyridine owing to an intense violet color. If this test(referred to in the following text as “Preussmann test”) is negative,the reaction is complete.

Synthesis of oligomeric ethylenimine having a terminal ethyleniminegroup 150 g of demineralized water were initially taken in a 1 lfour-necked flask which was equipped with a jacketed coil condenser,thermometer, 250 ml dropping funnel, 500 ml dropping funnel and gassingnozzle with N₂ connection and heated to 55° C. In the course of 1 hour,450 g of a 60% aqueous ethylenimine solution and a mixture of 6.5 g of37% strength hydrochloric acid and 152 g of demineralized water werethen added simultaneously. Thereafter, the reaction mixture was stirredfor a further 4 hours at 55° C. Thereafter, the mixture was cooled to15° C. and 11.6 g of a 25% strength aqueous sodium hydroxide solutionwere added. The product was then introduced into a glass vessel andstored therein at 5° C. The degree of oligomerization n (determined withthe aid of ¹H-NMR spectroscopy) was 6.84.

Oligoethylenimines having a terminal ethylenimine group, whose degree ofoligomerization n had the following values:

n=4.4n=4.7 andn=6.0were prepared analogously.

Example 1

In a 500 ml four-necked flask which was equipped with a refluxcondenser, dropping funnel and thermometer, 26.2 g of a 17% strengthaqueous solution of a polyvinylformamide which had a degree ofhydrolysis of 95%, comprised 95 mol % of vinylamine units and 5 mol % ofvinylformamide units and had a molar mass M_(n) (GPC) of 2000 gmol⁻¹ anda molar mass M_(w) (GPC) of 4100 gmol⁻¹ were initially taken, adjustedto pH 6.0 by addition of 1.06 g of 37% strength hydrochloric acid andheated to a temperature of 95° C. 204.0 g of a 35.1% strength aqueoussolution of an oligoethylenimine which comprised a terminal ethyleniminegroup and had a degree of oligomerization n of 4.7 were metered in thecourse of 1 hour. The reaction mixture was stirred for a further hour at95° C. Thereafter, the reaction was complete (Preussmann test negative).The reaction product had a molar mass M_(n) (GPC) of 2500 and a molarmass M_(w) (GPC) of 5800.

Example 2

In a 500 ml four-necked flask which was equipped with a refluxcondenser, dropping funnel and thermometer, 56.9 g of a 57.4% strengthaqueous solution of a polyamidoamine (M_(n) (GPC)=1950 gmol⁻¹, M_(w)(GPC)=3290 gmol⁻¹) prepared from diethylenetriamine and adipic acid wereinitially taken, adjusted to pH 5.9 with 21.5 g of 37% strengthhydrochloric acid and heated to a temperature of 95° C. 230.0 g of a35.1% strength aqueous solution of an oligoethylenimine which had aterminal ethylenimine group and a degree of oligomerization of 6.84 werethen added in the course of one hour. The reaction mixture was thenstirred for a further 2 hours at a temperature of 95° C. The reactionwas then complete (Preussmann test negative). The pH of the reactionmixture was 11. The polymer had an amine number of 293 mg KOH/g, a molarmass M_(n) (GPC) of 4900 gmol⁻¹ and a molar mass M_(w) (GPC) of 10 500gmol⁻¹.

Example 3

In a 500 ml four-necked flask which was equipped with a refluxcondenser, dropping funnel and thermometer, 74.6 g of a 57.4% strengthaqueous solution of a polyamidoamine (M_(n) (GPC)=1370 gmol⁻¹, M_(w)(GPC)=2280 gmol⁻¹) prepared from diethylenetriamine and adipic acid wereinitially taken, adjusted to pH 6.0 with 23.2 g of 37% hydrochloric acidand heated to a temperature of 95° C. In the course of one hour, 273.9 gof a 33.2% strength aqueous solution of an oligoethylenimine which had aterminal ethylenimine group and a degree of oligomerization n of 6.0were metered in. After addition of the oligoethylenimine, the reactionmixture was stirred for a further 2 hours at a temperature of 95° C. Thereaction was complete at this time (Preussmann test negative). The pH ofthe reaction mixture was 10.2. The polymer had an amine number of 297 mgKOH/g, a molar mass M_(n) (GPC) of 3500 gmol⁻¹ and a molar mass M_(w)(GPC) of 7400 gmol⁻¹.

Example 4

In a 500 ml four-necked flask having a reflux condenser, dropping funneland thermometer, 26.2 g of a 17% strength aqueous solution of apolyvinylformamide which had a degree of hydrolysis of 95%, comprised 95mol % of vinylamine units and 5 mol % of vinylformamide units and had amolar mass M_(n) (GPC) of 3100 gmol⁻¹ and a molar mass M_(w) (GPC) of8100 gmol⁻¹ were initially taken, adjusted to pH 6.0 by addition of 1.06g of 37% strength hydrochloric acid and heated to a temperature of 95°C. 230.0 g of a 35.1% strength aqueous solution of an oligoethyleniminewhich had a terminal ethylenimine group and had a degree ofoligomerization of 6.84 were then added in the course of one hour. Thereaction mixture was then stirred for a further hour at a temperature of95° C. After this time, the reaction was complete (Preussmann testnegative). The pH of the reaction mixture was 11. The polymer had anamine number of 357 mg KOH/g, a molar mass M_(n) (GPC) of 8500 and amolar mass M_(w) (GPC) of 24 000.

Example 5

In a 500 ml four-necked flask which was equipped with a refluxcondenser, dropping funnel and thermometer, 100.0 g of a 18% strengthaqueous solution of a polyvinylformamide which had a degree ofhydrolysis of 95%, comprised 95 mol % of vinylamine units and 5 mol % ofvinylformamide units and had a molar mass M_(n) (GPC) of 112 000 gmol⁻¹and a molar mass M_(w) (GPC) of 510 000 gmol⁻¹ and M_(w) (MALLS) of 240000 were initially taken, adjusted to pH 5.9 by addition of 5.6 g of 37%strength hydrochloric acid and heated to a temperature of 95° C. 230.0 gof a 35.1% strength aqueous solution of an oligoethylenimine which had aterminal ethylenimine group and had a degree of oligomerization of 6.84were then added in the course of one hour. The reaction mixture was thenstirred for a further hour at a temperature of 95° C. The reaction wasthen complete (Preussmann test negative). The pH of the reaction mixturewas 11. The polymer had an amine number of 292 mg KOH/g, and thefollowing values were determined for the molar masses:

M_(n) (GPC)=310 000 M_(w) (GPC)=570 000 M_(w) (MALLS)=390 000. Example 6

In a 1 l four-necked flask which was equipped with a reflux condenser,dropping funnel and thermometer, 40.2 g of an 18.8% strength aqueoussolution of a polyvinylformamide which had a degree of hydrolysis of97%, comprised 97 mol % of vinylamine units and 3 mol % ofvinylformamide units and had a molar mass M_(n) (GPC) of 34 000 gmol⁻¹and molar masses M_(w) (GPC) of 91 000 gmol⁻¹ and M_(w) (MALLS) of 54000 were initially taken, adjusted to pH 5.5 with hydrochloric acid andheated to 95° C. 200.0 g of a 45% strength aqueous solution of anoligoethylenimine which comprised a terminal ethylenimine group and hada degree of oligomerization of 4.4 were then added in the course of onehour. The reaction mixture was stirred for a further hour at atemperature of 95° C. The reaction was then complete (Preussmann testnegative). The pH of the reaction mixture was 10.2. The polymer had anamine number of 326 mg KOH/g, a molar mass M_(n) (GPC) of 200 000 and amolar mass M_(w) (GPC) of 235 000.

1. A graft polymer comprising one or more alkylenimine units as side chains, and comprising a grafting base selected from the group consisting of polymers having vinylamine units, polyamines, polyamidoamines and polymers of ethylenically unsaturated acids, wherein said graft polymer comprises exclusively one or more oligoalkylenimine side chains as the alkylenimine units.
 2. The graft polymer according to claim 1, wherein the oligoalkylenimine side chains have from 2 to 50 alkylenimine units.
 3. The graft polymer according to claim 1, wherein the oligoalkylenimine side chains have from 3 to 30 alkylenimine units.
 4. The graft polymer according to claim 1, wherein the oligoalkylenimine side chains have from 3 to 15 alkylenimine units.
 5. The graft polymer according to claim 1, wherein the oligoalkylenimine side chains consist of ethylenimine units.
 6. A process for preparing a graft polymer having one or more oligoalkylenimine side chains, comprising grafting at least one oligoalkylenimine which comprises a terminal aziridine group
 7. The process according to claim 6, wherein the oligoalkylenimine is an oligoethylenimine which comprises a terminal aziridine group.
 8. The process according to claim 6, wherein the grafting base has one or more polymers which have vinylamine units and comprise at least 50 mol % of vinylamine units.
 9. The process according to claim 6, wherein at least one polyamidoamine is the grafting base.
 10. The process according to claim 6, wherein at least one polyamine is the grafting base.
 11. The process according to claim 6, wherein a polymer of ethylenically unsaturated carboxylic acid is the grafting base.
 12. An antimicrobial coating material, comprising the graft polymer according to claim
 1. 